[Idr] FW: Review comments on BGP CT - from Jie Dong

[Susan Hares <[e-mail]>]

Jie, Kaliraj, Swadesh, DJ:

This email is to catch up the IDR WG on Jie Dong's comments on draft-ietf-idr-bgp-ct and Kalirja's comments to Jie's comments.

draft-ietf-idr-bgp-ct-18 is the latest draft.  My outstanding review comments are from Keyur and Jie.   My personal notes indicate Swadesh and/or feels Swadesh's comments on draft-ietf-idr-bgp-ct have not been address.  I would like each of you to acknowledge if you feel the information in the github repository (and on the list) concludes all the open issues for draft-ietf-bgp-ct?

Sue

From: Kaliraj Vairavakkalai <[e-mail]>
Sent: Monday, January 8, 2024 2:38 AM
To: Susan Hares <[e-mail]>; Reshma Das <[e-mail]>; Natrajan Venkataraman <[e-mail]>
Subject: Re: Review comments on BGP CT

Hi Sue, I think most of these comments are already recorded as github issues, and responded to in IDR. Ref: https://mailarchive.ietf.org/arch/msg/idr/ye7Zmg8Hq7-6JDLI1gZTwxiMyb8/ And as mentioned in t
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Hi Sue,

I think most of these comments are already recorded as github issues, and responded to in IDR.

Ref: https://mailarchive.ietf.org/arch/msg/idr/ye7Zmg8Hq7-6JDLI1gZTwxiMyb8/<https://shared.outlook.inky.com/link?domain=mailarchive.ietf.org&t=h.eJxNjbkSwiAURX8lQ608MAuQysJCHe2s7BBeErKpJO7jvxs623PmnvshN9-SPCLVOF6GHKDTrtXeVO6O1OFY0LMvIQDohhKc9fBCcexKub6KebZd7Ta8PB4eT7d_nSSQWUSakOtxnIacpTJTfAFDpT0Oy96-K2rOHUiui1gLISxjVhrFbSIkxsKktkBTMOCCJZlSiUpoGocqhmqjW-d1vaxvvbugp9NLcDa4f_b9ARnKQwI.MEYCIQDqAksJsEUOT-b6jhj1xU9s05LHa_Ow8_RD44w28X_4WwIhAJCfwIfUs_QcyvlV2Ua4m2QWR1O3OAvwlZqFrGqVi87y>


And as mentioned in this email, draft-ietf-idr-bgp-ct-18 had some changes to address these comments.



Below email does not specify which draft-version has been reviewed.

I will respond to a few new issues in below email. KV>

Yes, whatever issues are new/remaining, for those github issues can be raised. And yes, you can forward this email to IDR.

Thanks
Kaliraj



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From: Susan Hares <[e-mail]<mailto:[e-mail]>>
Date: Sunday, January 7, 2024 at 5:59 PM
To: Kaliraj Vairavakkalai <[e-mail]<mailto:[e-mail]>>, Reshma Das <[e-mail]<mailto:[e-mail]>>, Natrajan Venkataraman <[e-mail]<mailto:[e-mail]>>
Subject: FW: Review comments on BGP CT
[External Email. Be cautious of content]

Below are review comments from Jie Dong.  Are you Ok with me sending these to the IDR WG list?  I will also add issue to github to track issues.   I have pinged Keyur about responding to your comments on his review email?  Your are welcome to copy any email from IDR into the github.

Sue

From: Dongjie (Jimmy) <[e-mail]<mailto:[e-mail]>>
Sent: Sunday, January 7, 2024 10:04 AM
To: Susan Hares <[e-mail]<mailto:[e-mail]>>; Keyur Patel <[e-mail]<mailto:[e-mail]>>; Jeffrey Haas <[e-mail]<mailto:[e-mail]>>
Subject: RE: Review comments on BGP CT


Hi Sue,

Yes please help to forward these comments to the authors, thanks.

Best regards,
Jie

From: Susan Hares <[e-mail]<mailto:[e-mail]>>
Sent: Saturday, January 6, 2024 12:09 AM
To: Dongjie (Jimmy) <[e-mail]<mailto:[e-mail]>>; Keyur Patel <[e-mail]<mailto:[e-mail]>>; Jeffrey Haas <[e-mail]<mailto:[e-mail]>>
Subject: RE: Review comments on BGP CT

Jie:

Thank you for these comments.  May I forward these to Kaliraj and add these to the github issues for draft-ietf-idr-ct?

Sue

From: Dongjie (Jimmy) <[e-mail]<mailto:[e-mail]>>
Sent: Friday, January 5, 2024 10:26 AM
To: Susan Hares <[e-mail]<mailto:[e-mail]>>; Keyur Patel <[e-mail]<mailto:[e-mail]>>; Jeffrey Haas <[e-mail]<mailto:[e-mail]>>
Subject: Review comments on BGP CT


Hi Sue, Keyur and Jeff,

Here are some of my review comments on BGP CT, sorry for sending them late. I will continue my review on the rest of this document.


Abstract

Jie: It talks about using BGP-CT as a construct to realize IETF network slices. As I know, the network slice framework does not mention intent-based routing mechanisms. Thus the relationship between CT and network slicing is not that clear. Suggest to remove this or elaborate how CT can be used for realization of network slice.


In Section 2.1,

"Mapping Community: Any BGP CLA (e.g., Community, Extended Community) on an overlay route that maps to a Resolution Scheme. e.g., color:0:100, transport-target:0:100."

Jie: Is transport-target is also a mapping community? This contradicts with its definition (a community on an overlay route), or do you think BGP-CT is also overlay route?


In Section 4,

"A Transport Class is also configured with RD and import/export RT attributes. Creation of a Transport Class instantiates its corresponding TRDB and Resolution Schemes on that node."

 Jie: Suggest to provide some text here about why RD and RT are used for transport class. Such as the text in the last paragraph of section 6.


In Section 4.1,

"Tunnels (RSVP-TE, IGP FLEX-ALGO, SR-TE) with a latency no greater than 100ms."

 Jie: IGP Flex-Algo can use latency as metric type for path computation, while it may not be able to provide latency under a specific constraint.

KV> Ok. I will reconsider the example text.


In Section 4.1,

"These routes are used to resolve overlay routes including BGP CT, which may be further readvertised to adjacent domains to extend these tunnels."

Jie: Are BGP CT routes considered overlay routes or underlay routes?

KV> They can be both overlay and underlay routes. As overlay route, they resolve over SRTE/RSVP-TE/Flex routes.
KV> as Underlay routes e.g., Service routes resolve over CT routes.


In Section 5,

"any BGP Community Like Attribute (e.g. Community or Extended Community) may play this role."

 Jie: Can BGP large community and wide community be used as Mapping community? Maybe it is better to just limit it to community and extended community?


In Section 5,

"If a route contains more than one Mapping Community, it indicates that the route considers these distinct Mapping Communities as equivalent in Intent."

 Jie: In that case, which one should be used for resolution?

KV> The first one. But the order doesn't matter, since they map to same resolution-scheme.


In Section 6.2,

"When the length of Next hop Address field is 24 (or 48), the next hop
   address is of type VPN-IPv6 with an 8-octet RD set to zero
   (potentially followed by the link-local VPN-IPv6 address of the next
   hop with an 8-octet RD set to zero).  This follows Section 3.2.1.1 in
   [RFC4659]

   When the length of the Next hop Address field is 12, the next hop
   address is of type VPN-IPv4 with 8-octet RD set to zero."

 Jie: In which cases will the next-hop address include an RD set to zero?

KV> CT routes are sent with the nexthop including RD-set-to-zero.
KV> but the receiver is expected to allow nexthop without RD also.
KV> basically, conservative sender, and liberal receiver.

Best regards,
Jie